test(discovery): initialize workspace list in reader-stage fixture

Signed-off-by: Taylor Mutch <taylormutch@gmail.com>

Author: TaylorMutch

crates/openshell-server/src/grpc/service_discovery.rs

@@ -533,6 +533,7 @@ mod tests {
             &state,
             authed_request(WatchServiceRoutesRequest {
                 workspace_scope: request().workspace_scope,
+                workspaces: Vec::new(),
             }),
         )
         .await